Arterial hypertension in a murine model of sleep apnea: role of NADPH oxidase 2.

ABSTRACT

OBJECTIVES: To investigate whether NADPH oxidase 2 (NOX2), a major source of reactive oxygen species (ROS), contributes to the emergence of arterial hypertension in a murine model of sleep apnea. BACKGROUND: Obstructive sleep apnea (OSA) is a risk factor for arterial hypertension and it is linked to oxidative stress. METHODS: C57BL/6J mice were exposed to chronic intermittent hypoxia (CIH) for 6 weeks (5 days/week, 8 h/day, alternating cycles of hypoxia and normoxia, each lasting 120 s, nadir FiO2 7%). Blood pressure was monitored by telemetric catheters implanted into the abdominal aorta. Pharmacological inhibition of NOX by apocynin and NOX2-deficient mice were used to assess the role of NOX in CIH-induced arterial hypertension. NOX2 gene expression was measured by real-time PCR in different cardiovascular tissues. RESULTS: When compared with room air conditions, wild-type mice showed significant blood pressure elevations after exposure to CIH. This response was attenuated after treating animals with apocynin and in NOX2 (=gp91) knockout mice, whereas NOX2 was not upregulated in the heart, aorta, and femoral/carotid arteries of CIH mice. CONCLUSION: We suggest that the CIH-induced arterial hypertension is mediated by ROS derived from an activation of NOX2 within cells located outside the cardiovascular system.